Vol.:(0123456789) 1 3 Journal of the Brazilian Society of Mechanical Sciences and Engineering (2019) 41:182 https://doi.org/10.1007/s40430-019-1683-1 TECHNICAL PAPER Assessment of tool wear and mechanical properties of Al 7075 nanocomposite in friction stir processing (FSP) Navid Molla Ramezani 1  · Behnam Davoodi 1  · Mohammad Aberoumand 1  · Mojtaba Rezaee Hajideh 2 Received: 26 November 2018 / Accepted: 5 March 2019 / Published online: 20 March 2019 © The Brazilian Society of Mechanical Sciences and Engineering 2019 Abstract The aim of this study is to investigate the tool wear on friction stir processing of Al7075 base nanocomposite. The silicon carbide nanopowder was used as a reinforcing phase. The efects of input parameters including rotation speed, traverse speed and the pass number on the tool wear, microhardness and the topography were studied through the response surface meth- odology. Each of the input process parameters was selected in fve levels, and other parameters were considered constant. The friction stir tools were examined under a scanning electron microscope, and wear mechanisms were investigated at diferent conditions. The analysis of variance revealed that quadratic polynomial models are ftting to predict tool wear and microhardness. In addition, the results showed that tool wear also varied between 12 and 116 mm under diferent parameters. Furthermore, the rotation speed and pass number of 52.9% and 13.1%, respectively, have the greatest impact on tool wear. Traverse speed with more than 55% had the most efect on microhardness comparatively. Also, energy-dispersive spectros- copy analysis showed that with the highest percentage of Fe in rotation speed 900 rpm, traverse speed 50 mm/min and with three passes, the microhardness reached the highest level of 127.24 Vickers. Keywords Friction stir processing (FSP) · Tool wear · Microhardness · Nanocomposite · Al7075 1 Introduction Composites are composed of a matrix and reinforcing par- ticles. The reinforcing particles always include a fewer percent of composites. The particles can be fber or pow- der. Also, the reinforcing particles play a role in improv- ing the mechanical and surface properties of the matrix [1]. Composites can be in three types: metal (MMC 1 ), polymer (PMC 2 ) and ceramic (CMC 3 ). The use of metal-based com- posites is even more pervasive due to its widespread use and ease of manufacturing. The size of the conventional parti- cles is micro and nano. The nanograin-size particles provide excellent mechanical and surface properties. Nanoparticles are used to make more advanced metal-based composites. So that, metal-based nanocomposites are produced from the propagation of nanoparticles in the metal matrix phase [2]. Due to the high contact of reinforcing particle and metal matrix, the hardness and fnal strength of the workpiece increase [3]. FSP or friction stir processing is one method of improv- ing surface properties that can modify strength, grain size and surface roughness, etc. In the friction stir processing, a hard and rotating tool penetrates the workpiece and moves forward. The surface composite can be produced by fric- tion stir processing. This surface processing is a solid-state process, which is a high-efciency green process. To pro- duce the surface composite of the metal base matrix, it is necessary to insert the reinforcing ceramic powder in the metal matrix. Using this process, the reinforcing particles penetrate the metal surface at a certain depth (Fig. 1). One of the other benefts of friction stir processing can be referred to the refnement of the grain matrix and the positive and direct efect on the matrix hardness of the com- posite. With increase pass number in friction stir processing, Technical Editor: Lincoln Cardoso Brandão. * Behnam Davoodi bdavoodi@iust.ac.ir 1 School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran 2 School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran 1 Metal matrix composite. 2 Polymer matrix composite. 3 Ceramic matrix composite.